NOKIA Lumia 820 Overview :
Nokia Lumia 820 is situated in the mid-range class, a notch below the Nokia Lumia 920, yet promises a Windows Phone 8 experience identical to what a high-end device is expected to deliver. First thing you’ll notice about the Nokia Lumia 820 is its colorful outfit and the unibody look of its construction. The smartphone will be available with red, yellow, grey, cyan, purple, white and black. interchangeable shells, some of which allow the device to be charged wirelessly. The next thing that grabs the audience’s attention is the 4.3-inch display enhanced with ClearBlack technology allowing identical outdoor readability to that of the Lumia 920’s screen. Its resolution is 480 by 800 pixels, which is a bit underwhelming, yet still acceptable for a mid-range device. Moreover, the screen supports Super Sensitive touch technology, meaning that using some of the smartphone’s features is possible even if the user is wearing gloves. Underneath the hood of the Nokia Lumia 820 runs a dual-core Snapdragon S4 processor clocked at 1.5GHz paired with 1GB of RAM, which leads us to believe that performance won’t be an issue with the smartphone, especially knowing how smoothly Windows Phone runs even on less capable hardware. There is an 8-megapixel camera with Carl Zeiss optics and dual LED flash on the smartphone’s back, yet features like optical image stabilization and other PureView enhancements have been left out. Oh well, at least 1080p video can be captured at 30 frames per second. On the device’s front resides a VGA camera for video chats and the occasional self-portrait.

NOKIA Lumia 820 Sim Unlocking:
Unlock Telcel Mexico NOKIA Lumia 820 to use any where in the world with any supported service provider like

Hard Reset will erase all of your data
All described operations you are doing at your own risk.

First Method:

Device must be switch off.

Next press and hold Power button and after your device will vibrates, then once press Volume Down until you see exclamation sign on screen.

Then press this keys in sequence: Volume Up -> Volume Down -> Power button -> Volume Down

After that your phone will reset and reboots.

Done!

How to Update NOKIA Lumia 820 to latest Firmware:

Before starting a software update, we recommend that you make enough space on your phone. You need to have up to 1.5GB (depending on phone model) free phone memory to ensure that the software update goes smoothly. To check the available free space, go to Settings > Storage check.

There can be several updates available for your phone, so you may need to repeat the process a few times to get to the latest version. Follow all the update prompts so that you don’t miss out on any of the latest goodies. To see your current software version, go to Settings > Extras + Info.

We’ve recently announced that Windows 10 will be available later this year and it is our ambition to make an upgrade available to all Lumia smartphones running Windows Phone 8.1. In order to prepare your phone for Windows 10, you will need to have Lumia Denim (OS version 8.10.14219.341, or higher) installed.

Step 1: Your phone notifies you when an update is available for you. You can also check for updates by going to Settings > Phone Update and tapping Check for updates.

Tip! Use a Wi-Fi network to download the update and avoid mobile data transmission costs. Before starting the update, connect to a charger or make sure your phone has enough battery power (at least 50%). You might also need to make enough space on your phone for the update (up to 1.5 GB, depending on the phone model). To check for available free space, go to Settings > storage sense (storage check).

Step 2: To view and to install the updates, tap the notification message, and follow the instructions shown on your phone. You can install the update immediately, or postpone the update to a more convenient time.

Step 3: The update should take around 15-30 minutes, but a major update could take up to 2 hours to complete depending on your phone model. You are not able to use your phone during the update installation. Follow all the update prompts, and do not worry if your phone restarts several times during the process, that is completely normal.

Additional app updates from the Store could be needed to fully enable new features for your phone. You will get the app update notification on the Store app shortly after the software update.

From Lumia Denim update onwards, you can install phone updates more easily by scheduling them for a time that works best for you. You can find the Preferred install time option from Settings > Phone Update. Some of the phones now also support downloading updates to a memory card.